ENTROPY - OUR BEST FRIEND

Interdisciplinary Description of Complex Systems 3(1), 17-26, 2005 ENTROPY – OUR BEST FRIEND U. Kordeš Faculty of education – University of Ljubljana Ljubljana, Slovenia Regular paper Received: 10 May, 2005. Accepted: 1 July, 2005. We are the mirror as well as the face in it. We are tasting the taste this minute of eternity. We are pain and what cures pain, both. We are the sweet cold water and the jar that pours. Rumi SUMMARY The paper tries to tackle the question of connection between entropy and the living. Definitions of life as the phenomenon that defies entropy are overviewed and the conclusion is reached that life is in a way dependant on entropy – it couldn't exist without it. Entropy is a sort of medium, a fertile soil, that gives life possibility to blossom. Paper ends with presenting some consequences for the field of artificial intelligence. KEY WORDS entropy, autopoiesis, life, living systems CLASSIFICATION PACS: 89.75.Fb *Corresponding author, η: ; Faculty of education, Kardeljeva ploščad 16, SI – 1000, Ljubljana, Slovenia U. Kordeš WHAT IS LIFE? The aim of the present paper is search for new understanding of the role of entropy in connection to life and showing some consequences that arise from this. If I want to reach this goal, I have to start by listing some of the most common answers to question “What is life?” In searching for the principal, determining characteristic of life we normally tend to slip into the enumeration of its vital functions like metabolism, reproduction, growth etc. Karl von Frisch's book “Du und das Leben” from the year 1949 is an example of such an approach. The deficiencies, or at least borderline cases (crystals, viruses, the planet Earth…), of such definitions are not hard to find. Looking for the characteristic functions of living organisms is important for medical and some biological purposes, but it does not tell us enough about the phenomenon of life itself. Maturana and Varela [1] characterise the prevailing attitude of contemporary biology to the question of life as a combination of the physical-chemical and evolutionary approach. The first one explains biological processes from the point of view of chemical reactions going on inside living organisms. It focuses on processes such as cellular respiration and metabolism, the synthesis of proteins and also the genetic code, which is supposed to contain all information necessary for the synthesis of proteins and for life and the development of the organism in general. The second approach explains the emergence of biological processes as the result of random variations of the genetic code and natural selection of the phenotypes in which the genetic information gets realised. The first line of thought considers its basic biological unit to be the gene, for the second one this is the species1. Maturana and Varela [1, 2] do not question the physical-chemical foundation of living systems nor their gradual development through continuous interactions with the environment. They only doubt that the units of research selected this way (genes, species) could present us with a basis for our understanding of what is life in its essence. They claim that the question: What do all living systems have in common that makes us classify them as living beings? remains unanswered and always tacitly present somewhere in the background, even if most biologists tend to avoid it [1; p.74]. It is interesting that one of the most influential works on the question of life had not been written by a biologist but by a physicist. In his book “What is Life?” Erwin Schrödinger [3] presents a view of life starting from an utterly different perspective from contemporary biology. He takes into account the uniform nature of living beings, by which he manages to avoid reduction. Schrödinger suggests the following answer to the question: When do we consider something to be alive?; “When it ΄feeds΄ on negative entropy.” [3; ch.7]. The theory that living beings create negative entropy (the so-called syntropy or negentropy) has been picked up and developed in the last decades by the chemist Ilya Prigogine in his concept of dissipative structures (see e.g. [4]). A similar conception of the living can also be found in the work of one of the forefathers of cybernetics – Heinz von Förster, who compares living beings to the Maxwell demon in order to present the idea that living beings are actually entropy-retarders. It is important to notice that in all the variants of the described theory the basic units of research are living beings in their entirety and not just one selected function or process (e.g. reproduction or metabolism). If the entropic definition of life is to appear plausible, we cannot consider living beings to be closed systems, as in such systems entropy can only grow or remain unchanged. 18 Entropy – our best friend Living beings therefore must be open systems. But despite the fact that they are open, they are nevertheless also clearly separated from the environment in some way. This separation is, ontologically speaking, much stronger than for example the separation of the dewar (which can be considered to be an approximation of a closed system) from its environment. Thus, living systems are not closed in terms of the exchange of energy and matter, but they are “closed” in terms of preserving their identity. To emphasise these distinctions, Maturana and Varela distinguish between structurally and organisationally open or closed systems. Living organisms are thus structurally open and organisationally closed systems. Schrödinger gave an expanded entropy equation for this kind of systems: dS = deS + diS, where dS stands for the entire change of entropy of a living system, deS stands for the flow of entropy through the system and diS stands for the production of entropy inside the system due to irreversible changes occurring in it. While the diS member is always positive, the deS member can also be negative and in its absolute value bigger than diS, meaning that the entire change of entropy in an open system can be less than zero. Thus, an open system can change in the direction of increased orderliness. Of course, this ordering in open systems feeds on the order of the (closed) wider system, which contains these open systems – namely, the environment. This containing system still change in the direction of lesser order according to the second law of thermodynamics. The increase of entropy represents the flow of entropy that has negative value from the point of view of the contained open systems and enables them to increase their inner order. Under certain circumstances open systems can continuously perform work. For a system to be able to do that, it must not be in the state of stable equilibrium, rather, it has to “search” for such equilibrium [5]. Let us consider Bertalanffy's example of the water reservoir with high potential energy: one might open the reservoir and the water would sta (...truncated)